Ion beams can be and are used in substrate cleaning, co-deposition of materials, ion assisted deposition, ion milling, ion etching and the like. The present device can be and is advantageously used in any and all of the above mentioned applications.
In the prior art, the technique has been to produce plasma and direct the ions therefrom through a screen (the screen has a voltage which is negative to the plasma body to extract ions from the plasma, to form an ion beam) toward a substrate. This technique has worked reasonably well except that as the ions bombard the substrate, the substrate takes on a positive voltage bias and ions start being repelled by the substrate. The present device acts to provide a plasma external to the gun and this plasma which contains both ions and electrons provides ions for the ionic actions, but provides electrons to neutralize the positive charge on the substrate from the ion bombardment thereby mitigating the repelling effect.